Experiment Of BRB Frame, Simulink Simulation And The Equivalent Linear Design

Buckling-restrained brace（BRB） is a new type of energy dissipation dampingcomponent. Compared with the unbracedframe structure or ordinary bracedframestructure, BRB frame structure hasmuch higher energy dissipation capacity and greaterductility.This thesis adoptsBRBsto strengthenan RC frame building that was seriouslydamaged in the wenchuan earthquake, using them to increase the structure’s energydissipation capacity and seismic fortification lines.Shaking table tests weredesigned andconducted to compare the performance of the buckling-restrained bracedframe and theordinarybraced frame.The results show that, the horizontal stiffness of the BRB frame issignificantly increased, the displacement response to major earthquakes is significantlydecreased and the design objective of "no collapsetomajor earthquakes" could be metafter retrofitting.Because the section size of the braces is too large, contrast between BRBframe andordinary braced frame tests is not obvious. To further optimize the design of thecross-sectional dimension of the BRBs, this thesis usedthe simulation resultsfromSAP2000and plastic hinge model in FEMA to establishthe nonlinear constitutivelaw,take BRBs as energy dissipation devices,and performed the equivalent linearizationanalysis by the tool of MATLAB/SIMULINK.Simulation results show that theequivalent linearization model is consistent with the actual test results.The main content of the paper are as follows:1. Summarized the advantages, disadvantages and damage characteristics of theframe structures; discussed the common seismic strengthening methodsof framestructures; and briefly introduced the conception, development, and principle of BRBs.2. Designed a reduced-scale shaking table test model fora teaching building ofXuankou middle school which was severely damagedin the Wenchuan earthquake anduse BRB to retrofit it.Excited the model by the EL-Centro wave and Wolong wave withgradually increased intensities and record the seismic responses.Simulated andanalyzedthe shaking table model using SAP2000and compare the simulateddisplacement, velocity and acceleration of SAP2000with those of the shaking table test.Analyzed the accuracy of the simulation results for SAP2000,refine and extract thestatic and dynamic parametersof the original structure as the base of SIMULINKmodelling.3. Introducedthe performance-based seismic design theory and the equivalentlinearization research.Analyzed the response of the BRB supportframe： gave anequivalent linear design to BRB support based on bilinear elastic-plastic restoring forcemodel and got the equivalent damping and the equivalent stiffness；used the plastichinge to simulate the nonlinear response of frame structure.4. Introduced the MATLAB/SIMULINK dynamic system modeling and simulation principles.Designedthe SIMULINK modelsof “Linear BRB/nonlinearstructure” and “nonlinear BRB/nonlinear structure” respectively, to simulate thestructures with earthquake inputs.ComparedMATLAB/SIMULINK simulation resultswith the shaking table tests and SAP2000analysis results, analyzed the accuracy ofSIMULINKequivalent linearization.5. Proposed the performance objectivesfor the frame retrofitting. Redesigned thecore size of the BRBs and analyzed the frame’s seismic performance with the optimalBRB size based on the equivalent linearization rule.